Lining for high temperature furnaces

ABSTRACT

A lining for insulating the interiors of high temperature furnaces in which panels of insulating material are held firmly in place against the interior furnace surfaces by angle shaped hangers fastened to the furnace wall or ceiling surfaces. The hangers are protected by a thick insulation covering, the insulation being preferably of a flexible type which can be compressed during installation to insure firm attachment and compensation for shrinkage during subsequent furnace heating.

United States Patent 1191 Monagh an 1 1 July 1, 1975 1 1 LINING FOR HIGH TEMPERATURE FURNACES [75] Inventor: George J. Monaghan, Lewiston,

NYv

[73] Assignee: The Carborundum Company,

Niagara Falls, NY,

[22] Filed: Dec. 26, 1973 1211 Appl. No.: 428,649

[52] US. Cl. 266/43; 52/379; 52/486;

52/506; 110/1 A [51] Int. Cl. F27d H16 [58] Field of Search 264/30; 52/378, 379, 404,

[56] References Cited UNITED STATES PATENTS 1,535,220 4/1925 Gallagher 52/404 1,972,508 9/1934 Zeiner A l l r 52/378 2,074,874 3/1937 Vogel 110/1 A 2,270,297 1/1942 Hansel 110/1 A 2,581,989 l/1952 Weber H 110/1 A 3,077,058 2/1963 Hensel r 52/378 3,176,433 4/1965 Davies et a1. 52/487 3,523,395 8/1970 Rutter et a1 52/506 Primary Examiner-Gerald A. Dost Attorney, Agent, or Firm-David E, Dougherty; Clayton O. Obenland [57] ABSTRACT 8 Claims, 4 Drawing Figures w. 1 m m W 511 11 ,"EJFFITEDJULI SHEET FIGI SHEET LINING FOR HIGH TEMPERATURE FURNACES BACKGROUND OF THE INVENTION Many industrial processes which require high temperature furnaces must function for extended periods of time without costly shut downs for repairs. Such processes often require very large furnaces, and the loss of production due to a shut down for repairs can be a major problem. Since these furnaces may operate at temperatures of 2,000F or higher, the materials used therein are normally selected to withstand this service for extended periods of time.

Special refractory materials have been developed for use as furnace linings in such installations. In the past, these linings were limited to the use of refractory brick, which was laid up inside the furnace shell. Such linings were durable and are still used in a number of installations. They do, however, require the use of skilled labor and an extended heat up time for the lining to adjust to the desired furnace temperature. There are also problems associated with the materials of the furnace shell and the differences in rates of thermal expansion of the linings and the furnace shell.

In recent years, insulating panels comprised of vari ous refractory materials have been developed. These panels may be either rigid or flexible and their use in furnace linings have overcome many of the disadvantages previously discussed. If conditions permit, flexible panels are usually preferred as lining materials since they have excellent resistance to mechanical stresses, and are easier to install and repair, compared to rigid panels. However, there are still problems associated with the means used for the attachment of these panels to a furnace shell. One common procedure is to attach rods which project inwardly from the furnace wall or shell. Such rods may be attached by welding, if the furnace wall or shell is metallic. Corresponding holes are then made in the liner panels, and they are placed over the rods and fastened in place by friction clips or threaded holders which are attached to the projecting ends of the rods to hold the liner panels in place against the shell. These rods, and particularly the ends of the rods and the clips or threaded holders retaining the liner panels, are exposed to the heat of the furnace. These exposed parts have in some cases been covered with a refractory composition. In other cases, the rods and retainers are made of refractory materials. In practice, however, the liner material may shrink to a slight extent during prolonged exposure to hot furnace gases, thus allowing the gases to penetrate the liner at the points where it is held by the rods and connections of the attachment means; causing a failure at this point. This condition is more serious where the liner and attachment means is used on a furnace ceiling. Since these liners have otherwise been quite successful in furnace operations, a method of using this type of liner with a protected, easily fabricated attachment means is therefore highly desirable.

SUMMARY OF THE INVENTION The invention pertains to a furnace lining and to a method for installing the lining on the interior surfaces of a high temperature furnace in which hangers made from metal rods or strips are fastened at one end to the interior surface of the furnace wall, the extension of the hanger projecting within the furnace and being disposed in a substantially parallel relationship to the furnace wall. One or more flexible fibrous insulating liner panels are then impaled on the hanger extension, the edges of the panels being held by the hanger in firm longitudinal contact with the interior surface of the furnace. The flexible insulation liner panels are pressed down to form a firm bundle of insulation which surrounds and protects the metal hangers and provides a thick layer of insulation firmly held against the furnace interior surface. The lining may be modified, preferably by placing one or more backing panels of insulating material to cover the furnace interior surface after the hangers have been attached, followed by the impaling of the flexible panels on the hanger extensions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a hanger.

FIG. 2 is a sectional side view of the hanger attached to a furnace wall, with layers of insulation in place.

FIG. 3 is a isometric view of a portion of a furnace wall, showing the base positions of insulating panels and their supporting hangers.

FIG. 4 is an isometric view of a furnace wall similar to that of FIG. 3, showing the use of insulation with the inclusion of backing panels.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the invention makes use of hangers, such as generally indicated by 10 in FIG. 1. The hangers may be made from any suitable metallic rod or strip material, such as steel or brass, bent at an angle, preferably at an angle of about If rods are used, these may range from about A to inch or more in diameter, stainless steel rod of about 5/16 inch diameter being preferred. The rod or strip is bent so the longer second portion 12 is about three times the length of the shorter first portion 14. This proportion is not critical however, and the relative lengths may be varied as desired, depending on the thickness of the insulation used. The tip 13 of the longer second portion 12 is pointed at approximately a 45 angle, as shown in FIG. 1. The short first portion 14 is attached to the furnace wall surface 16 at the point 18, by any convenient means, preferably by welding (see FIG. 2). If desired, the portion 14 may be threaded and then fastened by bolting into an appropriate hole made in furnace surface 16 at point 18. The hanger attachment is shown in FIG. 2 in which it is seen that the portion 12 extends within the furnace and is preferably substantially parallel to the furnace wall surface 16.

After the hangers 10 are attached to the furnace surface 16, layers of flexible insulation liner panels 22 are then placed with their inner edges 23 in longitudinal contact with the furnace surface 16. The flexible liner panels are sections of fibrous insulating material of sub stantial thickness (approximately 1 to 6 inches) which may be cut from rolls or sheets to fit the dimensions de sired. The panels 22 are then placed over the pointed ends of the hanger portions 12 and are pressed down against the hanger portion 14. Flexible fibrous insulation panels are preferred since these may be easily impaled on the hanger portion 12 and may be readily pressed down to give a firm bundle of insulation. Additional layers of insulation are added until the hanger portion 12 is completely covered. This construction is shown in a side view in FIG. 2 and as an isometric view in P16. 3, where two hangers 12 are shown attached to the interior furnace surface 16, the attachment being made at the furnace floor level 24. The bundle of panels 22 rests against the floor 24 and is held in place with the panel edges 23 held against the interior surface 16 by the hangers 12. When flexible fibrous panels are used, these are pressed down to give a firm body of insulation. the degree of compression being such that a bundle of insulation normally about 15 inches in height is reduced to about 12 inches. Additional hangers are shown attached to the furnace wall surface 16 at points 18, these hangers acting to hold the panels below them under compression and to serve as supports for succeeding layers of insulation. The succeeding layers of insulation are installed in the same manner as the first, the attachment of hangers and the additional panels being continued until the furnace ceiling is reached. While the method of the invention has been described for insulating a furnace wall surface, it is not restricted to the wall but may also be employed for insulating the furnace ceiling surface as well.

A preferable method for installing the furnace lining includes the addition of one or more backing panels 20 which are placed against the surface 16 after the hangers 10 are attached (see FIG. 4). The backing panels 20 are preferably of substantially rigid material and may be of any of the customary cutable refractory insulating compositions such as magnesia or mineral wool, the insulation being customarily supplied in panels or blocks about 1 inch thick, l2 inches wide and 36 inches long. These serve as backing panels for the following flexible layers of insulation. Although a single backing panel is shown in the drawings, a second panel may be used over the first to give a thicker backing if desired.

With the backing panels and hangers in place, layers of flexible insulation panels 22 are then placed with their inner edges 23 in longitudinal contact with the interior surfaces of the insulating panels 20. The panels 22 are then placed over the pointed ends of the hanger portions 12 and are pressed down against the hanger portion 14, the insulation bundle being built up as previously described. An isometric view of a section of completed insulation is shown in FIG. 4. If desired, the backing panels 20 may be attached to the surface 16 by a suitable means, this attachment being considered desirable if the backing panels are used as part of the insu lation for the furnace ceiling surfaces.

The method of the invention is highly advantageous since the hangers are easily made of commonly available material and are readily installed as required. With the insulation in place, the hangers are surrounded by the insulation and protected from the hot furnace atmosphere. Since the flexible fibrous insulation used is compressed during installation, it resists the penetration of furnace gases, and the compression mounting increases the fiber strength and reduces shrinkage dur ing furnace operations. The density of the completed insulation bundle may be regulated as desired by the degree of compression applied during installation, the thickness of the insulation depending, of course, on the width of the insulating panels used. The use of fibrous refractory material, aluminasilica, fibers for example, gives furnace insulations which are quickly and easily installed and are effective at temperatures ranging from 23DO to as much as 2600F.

l claim? 1. A lining for the interior surface of a furnace, comprising:

a. at least one metallic hanger for attachment to the interior surface of the furnace, said hanger having a first portion attached to said surface and a second portion projecting within said furnace and disposed in substantially parallel relationship to said surface; and

b. at least one insulation panel comprised of flexible fibrous refractory material, said panel being impaled over and completely penetrated by said second portion of said hanger, one longitudinal edge of said panel being held by said hanger in firm longitudinal contact with the interior surface of said furnace to form the lining.

2. A lining according to claim 1 which further comprises at least one hacking panel of insulating refractory material, said panel disposed in contact with said interior surface and in parallel relationship thereto, said backing panel covering said interior surface and said hanger at said surface attachment, said backing panel forming a surface for longitudinal contact with the longitudinal edge of said flexible insulation panel impaled upon said hanger.

3. A lining according to claim 2 in which the said backing panel comprises a substantially rigid insulating material.

4. A lining according to claim 1 in which said metallic hanger is bent substantially at a right angle and said second portion is pointed at the end thereof.

5. A method for lining the interior surfaces of a high temperature furnace, the method comprising:

a. forming at least one hanger of angular shape from an elongated piece of metal;

b. attaching rigidly one end of said hanger to the interior furnace surface, the other end of the hanger projecting within the furnace, substantially parallel to said surface; and

c. impaling at least one flexible fibrous refractory insulating panel over the projecting end of said hanger, said projecting end completely penetrating said insulating panel, and one longitudinal edge of said panel being in longitudinal contact with said interior surface.

6. A method according to claim 5 which further comprises the step of placing at least one backing panel of insulating refractory material in contact with said surface and in parallel relationship thereto, said backing panel covering said surface and said hanger at said surface attachment, said backing panel being placed thereon prior to the step of impaling said flexible fibrous insulating panel over said hanger, said flexible fibrous insulating panel having one longitudinal edge in contact with the interior surface of said backing panel.

7. A method according to claim 6 in which said backing panel comprises a substantially rigid insulating material and said panel is attached to said interior surface.

3. A method according to claim 5 which further comprises the step of sharpening the end of said hanger which projects within said furnace. k 

1. A lining for the interior surface of a furnace, comprising: a. at least one metallic hanger for attachment to the interior surface of the furnace, said hanger having a first portion attached to said surface and a second portion projecting within said furnace and disposed in substantially parallel relationship to said surface; and b. at least one insulation panel comprised of flexIble fibrous refractory material, said panel being impaled over and completely penetrated by said second portion of said hanger, one longitudinal edge of said panel being held by said hanger in firm longitudinal contact with the interior surface of said furnace to form the lining.
 2. A lining according to claim 1 which further comprises at least one backing panel of insulating refractory material, said panel disposed in contact with said interior surface and in parallel relationship thereto, said backing panel covering said interior surface and said hanger at said surface attachment, said backing panel forming a surface for longitudinal contact with the longitudinal edge of said flexible insulation panel impaled upon said hanger.
 3. A lining according to claim 2 in which the said backing panel comprises a substantially rigid insulating material.
 4. A lining according to claim 1 in which said metallic hanger is bent substantially at a right angle and said second portion is pointed at the end thereof.
 5. A method for lining the interior surfaces of a high temperature furnace, the method comprising: a. forming at least one hanger of angular shape from an elongated piece of metal; b. attaching rigidly one end of said hanger to the interior furnace surface, the other end of the hanger projecting within the furnace, substantially parallel to said surface; and c. impaling at least one flexible fibrous refractory insulating panel over the projecting end of said hanger, said projecting end completely penetrating said insulating panel, and one longitudinal edge of said panel being in longitudinal contact with said interior surface.
 6. A method according to claim 5 which further comprises the step of placing at least one backing panel of insulating refractory material in contact with said surface and in parallel relationship thereto, said backing panel covering said surface and said hanger at said surface attachment, said backing panel being placed thereon prior to the step of impaling said flexible fibrous insulating panel over said hanger, said flexible fibrous insulating panel having one longitudinal edge in contact with the interior surface of said backing panel.
 7. A method according to claim 6 in which said backing panel comprises a substantially rigid insulating material and said panel is attached to said interior surface.
 8. A method according to claim 5 which further comprises the step of sharpening the end of said hanger which projects within said furnace. 